The present disclosure relates to communication networks, and, in particular, to methods, systems, and computer program products for provisioning a network service in a virtualized environment.
In a typical service provider environment, a Network Service (NS) may be provided on purpose-built hardware, which in turn is vendor gnostic. Scaling may be an expensive and time consuming affair, which may adversely affect both operational and capital expenses. Software Defined Networking (SDN) and Network Function Virtualization (NFV) may be used to remove the dependency of a NS on the hardware and use virtualization to treat the NS like a software application that can be provisioned on a virtual machine. Virtualization may result in quicker scaling, better use of infrastructure cost and may provide service providers with easier and cheaper options for dedicating a NS for each subscriber as opposed to sharing a NS across multiple subscribers.
A Virtual Network Function (VNF) is a virtualization of a network function in, for example, a legacy non-virtualized network. A VNF may comprise multiple internal components. For example, one VNF can be deployed over multiple Virtual Machines (VMs), where each VM hosts a single component of the VNF. In other examples, the VNF can be provisioned in a single VM.
A VNF forwarding graph VNF FG defines the sequence of network functions that packet traffic traverses when providing a NS. A VNF provider may implement the software for a VNF and may provide. VNF and NFV management may refer to the operational systems supporting the Network Function Virtualization Infrastructure (NFVI).
A Physical Network Function (PNF) is an implementation that may be part of an overall network service, but is not virtualized. A physical network function may be provisioned, managed, and operated by a network service provider. Examples of physical network functions may include, but are not limited to, a physical access or backbone network, a standalone VM.
The boundary between a VNF FG and physical network functions may be specified by the network service provider. The boundary may be based upon fields in a packet header that are the source or destination of packets entering or exiting a VNF across an interface from/to a physical network function. For example, a VLAN on an Ethernet port may connect a physical port (e.g., on a NIC or a switch) in the NFVI to a physical/logical port on a PNF.
The net outcome that contributes to the overall service is that certain groups of packets follow the same path through the VNF FG. Note that the VNF functionality, configuration and state determine the packet flow through the VNF FG and the VNFs traversed may differ in each direction for packets of the same bi-directional flow.
The NFV network infrastructure provides connectivity services between the VNFs that implement the forwarding graph links between VNF nodes in hardware and/or software as controlled by NFV management and orchestration. The NFV network infrastructure may contain functions including, for example, traffic classification, tunnel encapsulation/decapsulation, traffic steering and/or some forms of load balancing.
Thus, an end-to-end network service (e.g. mobile voice/data, Internet access, a virtual private network) can be described by a VNF FG of interconnected Network Functions (NFs) and end points interconnected by supporting network infrastructure. The end-to-end network service is what an operator provides to customers. These network functions can be implemented in a single operator network or interwork between different operator networks. The underlying network function behavior contributes to the behavior of the higher-level service. Hence, the network service behavior is a combination of the behavior of its constituent functional blocks, which can include individual NFs, NF Sets, NF Forwarding Graphs, and/or the infrastructure network.
The end points and the network functions of the network service are represented as nodes and correspond to devices, applications, and/or physical server applications. A VNF FG can have network function nodes connected by logical links that can be unidirectional, bidirectional, multicast and/or broadcast. A simple example of a forwarding graph is a chain of network functions—physical and/or virtualized.
An example of such an end-to-end network service can include a smartphone, a wireless network, a firewall, a load balancer and a set of CDN servers. The NFV area of activity is within the operator-owned resources. Therefore, a customer-owned device, e.g., a mobile phone is outside the scope as an operator cannot exercise its authority on it. However, virtualization and network-hosting of customer functions is possible and is in the scope of NFV.
FIG. 1 illustrates a communication network 100 for providing a network service in a virtualized environment. The communication network includes a physical network that supports four hosts: host 1, host 2, host 3, and host 4. Each host supports two virtual machines via a hypervisor. Host 1 supports virtual machines VM1 and VM2 via hypervisor 1, Host 2 supports virtual machines VM3 and VM4 via hypervisor 2, Host 3 supports virtual machines VM5 and VM6 via hypervisor 3, and Host 4 supports virtual machines VM7 and VM8 via hypervisor 4. In the example of FIG. 1, the communication network supports three network services corresponding to VNF FGs 105, 110, and 115. VNF FG 105 comprises VNF1, VNF2, and VNF3 to support a first network service. Thus, the first network service uses resources from two different hosts. VNF FG 110 comprises VNF4, VNF5, and VNF6 to support a second network service. Similar to the first network service, the second network service uses resources from two different hosts. VNF FG comprises VNF7 and VNF8 to support a third network service. The third network service uses resources from a single host.
In providing an end-to-end network service a service provider may, for example, configured a communication network with two PNFs with several VNFs therebetween. These VNFs may be provided by one or more VNF providers or vendors. These VNFs may have some metadata associated therewith that describe the essential characteristics of the VNF. The actual network service is the set of all possible packet flows that traverse the VNF FG and any PNFs. A network service involves information (as well as logic in the VNFs themselves) that make use of the VNF FG
An example of a VNF FG commonly encountered is where packets traverse a VNF implementation of a router, an intrusion detection device, a firewall NAT, and a load balancer that distributes traffic to a pool of servers. Another example is a subscriber-oriented service for wireless users deployed at a NFVI-PoP on a wireless Gi LAN or in a wireline network. Service chain is another term for a VNF FG where each node is chained in a service provider environment to deliver a particular service to a customer or subscriber.